Selector switch brush



Jan. 30, 1940. c. N. HICKMAN SELECTOR SWITCH BRUSH Filed June 21, 1938INVE/V TOR C. N. H/CKMAN 69 M ATTORNEY I terially reduced.

Patented Jan. 30, 1940 SELECTOR res FFiCE I Clarence'N. Hickman, JacksonHeights, N. Y.

assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,a corporation of New York This invention relates to a brush set for usein va selector switch and more particularly to a brush set for aselector switch cooperating with a panel bank of terminals.

Panel type selector switch frames are provided with one or more flat orpanel banks of terminals with which the brush sets of a plurality ofselector switches cooperate.

mounted one above the other or side by side. In

some types of selector switches the brush sets are rigidly mounted onelevator rods which are guided 'in supports mountedon the switch frameand in other types they are slidably mounted on guide rods which arerigidly secured at their ends to end members of the frame. In eithercase, due to the extensive area of the banks, there may be a tendencyfor the brush supporting rod to vibrate laterally with respect totheface of the banks thereby causing a lateral sliding movement of thebrushes on the terminals of the banks with which they are engaged. Thevibratory movement of the supporting rod may be due to buildingvibrations imparted to the switch frame or to vibrations set up in theframe due to the operation of It is therefore the object of the presentinvention to improve the contact engagement between selector switchbrushes and bank terminals I whereby the introduction of noise into thespeech transmission circuit extending thereover is ma- 'In accordancewith the invention, this object is attainedby constructing each brush ofthe brush set so as to have rigidity in the direction of brush travelover a row of terminals of the terminal bank, but to have flexibility ina direction at right angles to the contact faces of the bank terminalsfor insuring good contact pressure between the brush and the bankterminal and to have flexibility in a direction perpendicular to theface of narrow-Vertical arms united at their ends to two narrowhorizontal arms. The spring is secured at These banks are either shown)is bent at right angles to the plane of the spring to the centerpo-rtionof which the brush shoe is attached. The rectangular form of thespring renders it rigid in the direction of travel of the brush shoeover the row of bank terminals, but the narrow end arms thereof renderthe spring resilient in such a direction as to hold the brush shoefirmly against the contact surface of a bank terminal with which itengages. The outer vertical arm of the spring to which the brush shoeiss'ecured being bent at right angles to the plane of the spring is thusrendered resilient in a direction at right anglesto the face of theterminal bank whereby the brush shoe, forced into frictional engagementwith the contact surface of the bank terminal by. the resilient end armsof the springQdoes not tend to slide on the terminal should the brushcarriage vibrate in a direction reference may be had' to the followingdetailed panying drawing in, which;

Fig. l is a perspective view of a brush carriage having brush springs.embodying the present invention; v

- Fig. 2 is an exploded perspective view of the brush carriage shown inFig. 1; =1

Fig. 3 is a bottom end View of the brush carriage shown in Fig. 1 and aportion of the terminal bank; and

Fig. 4 shows a modified form of a brush spring.

The brush carriage has been disclosed as suitable for use in a selectorof the type disclosed in Patent 2,123,229, granted July 12, 1933, to W.W. Carpenter andR. F. Mallina, but is will be obvious that the inventionis equally applicable to other well-known types of selector switches.The carriage comprises a substantially U-shaped frame in the arms I and2 on which are positioned fiber bushings 3 and i bymeans of which thecarriage is slidably supported on a suitable guide rod (not The guiderod is secured at its ends to the end brackets of the switch. Thevertical portion 5 of the frame is bent at right angles to form anextension 5 to which the brush springs are secured.

The brush carriage is provided with four brush springs l, 8, 9 and ill,the brush spring I being supported on one face of the extension 6 andindescription readin connection with'the accom- 'sulated therefrom by afiber separator H and the springs 8, 9 and it being assembled on theother face of the extension 5. The'spring 8 is in sulated from theextension t by aninterposed ,fiberseparator l2 and thesprings 8, 9 andI0.

are insulated from each other by interposed separators l3, it and N3 offiber or other suitable material. Positioned between the separators I3and I4 is a plate is to the ends of which a tape belt for traversing thebrush carriage may be secured. For securing the springs, separators andplate iii in assembled position on the extension 6, screws ii and it areprovided, each having .a sleeve I?) of insulating material thereon,which extend through aligned holes in the outer clamping plate 20,insulating separator 2!, spring I, separator 2!, extension 6, separator12, spring 8, separator i3, plate [6, separator [4, spring 9,

separator l5, spring i0, separator ZZinto thread ed holes in theclamping plate 23. By means of the separators and the sleeves, the brushsprings are completely insulated from each other and from the brushcarriage. bearing between the heads of screws I? and i8 and the clampingplate 20, washers 2 3 are interposed between the screw heads and theinsulating sleeves).

Each brush spring is of substantially rectangular outline and has itsinner portion stamped out to form two narrow vertical arms as indicatedat and 26 in connection with spring I, joined at their ends by twonarrow horizontal arms 27 and 28. The arm 25 is enlarged at itsmid-portion and provided with holes through which the clamping screwsand insulating sleeves may extend as previously described. The arm 26 isbent at right angles to the plane of the arms 21 and 28 and is formedwtih a tongue 29 extending forwardly at right angles therefrom orparallel to the plane of arms 2? and 23 on which the brush shoe 30 issecured by staking or in any other desired manner. The brush shoe has abody of insulating material in one face of which a contact member 3| isembedded. The ends of the contact member are secured to the tongue 29 bysolder or other suitable means.

The springs l and iii are similarly constructed. The two inner springs 8and 9 are identical in form and similar to spring 1, except that the arm26 of each spring is first bent at right angles to the plane of thespring and then bent outwardly and backwardly on itself in a U-shape asindicated by the numeral 32. The springs 1 and Hi and 8 and 9 areassembled as most clearly shown in Fig. 3 with their arms 26 extendingin opposite directions in order that the brush shoes carried thereby maybe properly spaced apart for engagement with rows of terminals of theterminal bank 33. A

ihe rectangular shape of each brush spring provides rigidity in thedirection of travel of the brush shoe over a row of bank terminals orvertically as viewed in Figs. 1 and 2, and the narrow end arms 21 and28'provide sufficient resiliency in a directionat right angles to thecontact surfaces of a row of terminals as viewed in Fig. 3 to insurethat the contact member 3! of the brush shoe will be pressed into a firmcontact 7 with the contact surfaces of the bank terminals.

The arm 26 of eachspring being bent as shown at right angles to theplane of the arms 21 and 23 affords a support for the brush shoe carriedthereby which is flexible in a direction at right angles to the facev ofthe bank as viewed in Fig. 3 whereby if there is a relative lateralmovement between the guide rod on which the brush carriage is supportedand the face of the terminal bank or between the brush carriage and theface of the bank, the arm 26 will flex without causing the brush shoe tofollow the lateral movement To provide a suitable of the brush carriage.The brush shoe is thus maintained in firm engagement with the bankterminal upon which it is resting whereby noise 1 from a contact over abrush which may be included in a talking circuit is eliminated orsubstantially reduced.

As an alternative construction, the brush spring may be formed as shownin Fig. 4 with two vertical arms and 36 joined at their ends by thehorizontal arms 37 and 38. The arm'35 is provided with an enlargedcentral portion by means of which the spring is supported on the brushcarriage and the arm 36 has its inner and outer edges bent at rightangles to the plane of the arms 31 and 38 to form parallel members 39and M2. The members 39 and 4!) are joined only at their points ofjuncture with the arms 31 and ported on the cross member M between themembers 39 and 40 and is held in position by a'rivet and by the crossmember 4! whereby they have lateral flexibility. The brush shoe 42 issup-- i3 extending therethrough and. through the 1 members 39 and 40.

What is claimed is:

1. A brush for sliding engagement with thecontact. faces of theterminals of a terminal bank comprising a contact shoe and a frame ofspring material for supporting said shoe, said frame being rigid in thedirection of travel of said shoe over the terminals of the bank andflexible in a I direction at right angles to the contact faces of theterminals and also in a direction at right angles to the face of thebank.

2. A brush for sliding engagement with the contact faces of theterminals of a terminal bank comprising a I contact shoe and a frame ofspring material for supporting said shoe, said frame having a rearmember for attachment to a brush carriage, laterally extending endmembers rigid in the direction of travel of said shoe: over theterminals of the bank, but flexible in a direction' at right angles tothe contact. faces of the terminals and a-front member to the centerofwhich said shoe is secured, flexible in EidiIBCtiOIlBJl right angles tothe face of the bank.

3. A brush for sliding. engagement with thev contact faces of theterminals of a'terminal bank terminals ofthe bank, but flexible inadirection T atright angles to the contact faces of the ter-' minalsand. a front member to the center of which said shoe is'secured bent atright angles to the plane of said end members whereby it is'rendered'l irigid in a direction at right angles to the contact, faces of theterminals but flexible in a direction: 9 i

at right angles to the face of: the bank.

4. A brush for sliding engagementfw-ith the Contact faces of theterminals of a terminal bank, comprising a-contact shoe anda frame ofspring" material for supporting said shoe, said frame having a rearmember for attachment to a brush carriage, end members lying in theplane of said:

rear member and extending forwardly therefrom having rigidity in thedirection of travel of said shoe over the terminals of the bank andflexi-- bility in a directionat right angles to the contact faces of theterminalaafront member joining the forward ends of said end members andbent at right angles to the plane thereofwhereby said front member hasflexibility in a direction at i right angles to the face of the bank anda contact shoe supporting tongue bent vat right angles from. the centralportion of one edge of said front member to which said shoe is secured.

5. A brush for sliding engagement with the contact faces of theterminals of a terminal bank comprising a frame of spring material, saidframe having a rear member for attachment to a brush carriage, endmembers lying in the plane of said rear member and extending forwardlytherefrom having rigidity in the direction of travel of the brush overthe terminals of "the bank and flexibility in a direction at rightangles to the'contact faces of the terminals, a front."

member joining the forward ends of said end members having its edgesbent at an angle to the plane thereof to form substantially parallelribs having flexibility in a direction at right angles

